Modular femoral provisional

ABSTRACT

A provisional prosthetic system that replicates the characteristics of a corresponding, nonprovisional femoral prosthesis. The provisional prosthetic system may include a frame component and a shell component. The frame component of the provisional prosthetic system may be configured to be attached directly to a resected femur. In one exemplary embodiment, the frame component is impacted onto the resected femur to firmly seat therewith. Once the frame component is secured to the resected femur, a shell component of the provisional prosthetic system may be positioned on and secured to the frame component. In one exemplary embodiment, the frame component is made from a metallic material. This allows for the frame component to maintain the rigidity necessary to facilitate proper trialing. In another exemplary embodiment, the shell component is a plastic.

BACKGROUND

1. Field of the Invention

The present invention relates to a provisional prosthetic system and thesurgical methods for utilizing the same.

2. Description of the Related Art

Prostheses are commonly utilized to repair and/or replace damaged boneand tissue in the human body. For example, a knee prosthesis may beimplanted to replace damaged or destroyed bone in the tibia and/or femurand to recreate the natural, anatomical articulation of the knee joint.To implant a prosthesis, orthopedic surgery is performed which requiresthe creation of an incision in the skin of the patient and maynecessitate the retraction of surrounding tissue to provide the surgeonwith access to the surgical site.

To facilitate the implantation of a prosthesis, modular prostheses maybe utilized. Modular prostheses have several individual, distinctcomponents which are connected together to form the final, implantedprosthesis. For example, a modular knee prosthesis may includeindividual femoral, tibial, and patellar components which are connectedtogether to form the final, implanted knee prosthesis. Additionally, onecomponent, e.g., a femoral implant in a modular knee prosthesis system,may be selected from several different femoral components having variousconfigurations, all of which are included in the modular prosthesissystem. By selecting the femoral component that best accommodates anindividual patient's anatomy, the surgeon may assemble a prosthesis thatmore closely approximates the natural anatomy of the patient.

In addition to the final, implanted components of a modular prosthesissystem, a modular prosthesis system may also include provisionalcomponents which replicate the size and shape of the final, implantedcomponents of the modular prosthesis system. The use of provisionalcomponents provides the surgeon with the ability to test the ultimateconfiguration of the prosthesis prior to the implantation of the finalcomponents. By trialing, i.e., testing, the surgeon is able to determinewhether the fit, alignment, and range of motion provided by the finalprosthesis will approximate the patient's natural anatomy. Additionally,as many implants achieve some measure of press fit with the resectedbone, it is important that the provisional components maintain similarstiffness to the implant so that implant fit to bone can be checkedprior to implantation. To ensure that the provisional componentsaccurately replicate the function of the final, implanted components,the provisional components are dimensionally equivalent to the implantedcomponents and are frequently manufactured from the same material.

SUMMARY

The present invention relates to a provisional prosthetic system and thesurgical methods for utilizing the same. In one embodiment, theprovisional prosthetic system replicates the characteristics ofcorresponding, nonprovisional femoral prostheses. In this embodiment,the provisional prosthetic system includes a frame component and a shellcomponent. The frame component of the provisional prosthetic system maybe configured to be attached directly to a resected femur. In oneexemplary embodiment, the frame component is impacted onto the resectedfemur to firmly seat therewith. Once the frame component is secured tothe resected femur, the shell component of the provisional prostheticsystem may be positioned on and secured to the frame component. In oneexemplary embodiment, the frame component is made from a metallicmaterial. This allows for the frame component to maintain the rigiditynecessary to facilitate proper trialing. In another exemplaryembodiment, the shell component is a plastic. In yet another exemplaryembodiment, the shell component is fabricated by injection molding.

To ensure that a provisional and, ultimately, a nonprovisional that hasthe characteristics most suited for an individual patient are selected,the provisional prosthetic system may include a plurality of shellcomponents having different characteristics, e.g., different sizes,orientations, and/or designs that correspond to available nonprovisionalprostheses. For example, if the prosthesis includes three differentnonprovisional implants having different sizes, three provisionalimplants would be included in the prosthesis system which correspond insize to the three nonprovisional implants. Thus, a surgeon may attach afirst shell component to the frame component of the provisionalprosthetic system and trial, i.e., test, the same. If the surgeon is notsatisfied with the results of the current shell component, the surgeonmay remove the shell component from the frame component and attach adifferent shell component having different characteristics, until thebest fit for an individual patient is identified.

By utilizing the provisional prosthetic system of the present invention,numerous benefits are realized. For example, by utilizing the framecomponent and shell component design of the present system, only asingle frame component is attached to the resected femur. Thus, the needto impact and remove various provisional components from the resectedbone is eliminated and wear of the natural bone stock during thetrialing of the provisional components is lessened. Additionally, byeliminating the need to manufacture the shell components of theprovisional prosthetic system from a metallic material, the weight ofthe full complement of provisional components is substantially lessened.This decreases the burden on operating room personnel and hospital staffto stock, inventory, clean, and transport the full complement ofprovisional components. Moreover, by manufacturing the shell componentsof the present provisional system from plastic, for example, the cost ofproducing the same is decreased.

Further, because a plurality of different shell components may beattached to a single frame component, the total number of provisionalcomponents in any given provisional system may be decreased. Forexample, in an implant system having femoral components for standardsize, plus size, and minus size for each of the left knee and the rightknee, a single frame component may be designed to accept all sixconfigurations of the corresponding shell components. Thus, a singleframe can be combined with the differing shell components to formprovisional components that accurately replicate the characteristics ofthe six corresponding nonprovisional implants.

By providing a full complement of provisional components having a massand volume substantially less than that of a complement of standardprovisional components, a hospital may be more likely to stock theentire system. Additionally, a surgeon may request the entire complementof components in the operating room and thus the surgeon may be able toachieve better extension and flexion gap balancing, without the need toperform additional bone cuts or to extensively test the flexion andextension gaps.

In one form thereof, the present invention provides a modularprovisional system, including a frame component configured to be securedto the distal end of a femur; and a shell component configured to bereleaseably secured to the frame component, the frame component and theshell component cooperating to form a provisional implant whichreplicates the characteristics of at least one nonprovisional componentof a prosthesis system.

In another form thereof, the present invention provides a modularprovisional system, including a frame component having first engagementstructure, the frame component configured for securement to the distalend of a femur; and a shell component having a frame contacting surfaceand an articulation surface, at least a portion of the frame contactingsurface configured to engage the first engagement structure of the framecomponent to secure the shell to the frame, the articulation surface ofthe shell component shaped to replicate natural femoral condyles,wherein the frame component and the shell component cooperate toreplicate a characteristic of at least one nonprovisional component of aprosthesis system.

In another form, thereof the present invention provides a method oftrialing a femoral implant including the steps of attaching a framecomponent to the distal end of a femur; attaching a shell componenthaving an articulation surface to the frame component, wherein the framecomponent and the shell component cooperate to form a first provisionalimplant; trialing the first provisional implant formed by the framecomponent and the shell component.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention,and the manner of attaining them, will become more apparent and theinvention itself will be better understood by reference to the followingdescription of an embodiment of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 is an exploded perspective view of one embodiment of theprovisional prosthetic system and depicting a resected femur;

FIG. 2 is another perspective view of the embodiment of FIG. 1, takenfrom a posterior aspect;

FIG. 3 is another perspective view of the embodiment of FIG. 1 takenfrom a medial aspect;

FIG. 4 is an exploded perspective view of the provisional prostheticsystem according to another exemplary embodiment; and

FIG. 5 is an assembled, perspective view of the provisional prostheticsystem of FIG. 4;

FIG. 6 is a partial assembled view of the provisional prosthetic systemof FIG. 1; and

FIG. 7 is an assembled view of the provisional prosthetic system of FIG.1.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrates preferred embodiments of the invention and suchexemplifications are not to be construed as limiting the scope of theinvention any manner.

DETAILED DESCRIPTION

As shown in FIGS. 1-3, femoral provisional 10 includes frame component12 and shell component 14. Shell component 14 may be attached to framecomponent 12, as shown in FIG. 7, to form assembled femoral provisional10, as described in detail below. Referring to FIGS. 1-3, framecomponent 12 of femoral provisional 10 is configured for directattachment to femur 16. As shown in FIG. 1, femur 16 includes resecteddistal end 18 having apertures 20 and cutout 22 formed therein. Resecteddistal end 18 of femur 16 is fully resected, i.e., all of the cutsnecessary for implantation of a final, nonprovisional femoral componenthave been made. In another exemplary embodiment, resected distal end 18may include only a portion of the cuts necessary to facilitateimplantation of the final, nonprovisional femur component. In thisembodiment, femoral provisional 10 may be utilized to facilitate asurgeon's determination of the location for making the remaining cuts tofemur 16.

In one exemplary embodiment, frame component 12 is formed from ametallic material, e.g., formed from a metal, a metal alloy, or amaterial having properties that are substantially similar to a metal ormetal alloy. This provides frame component 12 with the necessaryrigidity to represent the rigidity of the corresponding nonprovisionalcomponent on the resected bone and retain shell component 14 in theproper position during trialing. Frame component 12 of femoralprovisional 10 includes bone contacting surface 24 and posts 26, bestseen in FIG. 2. Bone contacting surface 24 of frame component 12 isshaped to mate with resected distal end 18 of femur 16 and posts 26 aresized to be received within apertures 20. Apertures 20 of femur 16 maybe formed by drilling, reaming, or any other known technique. Apertures20 are sized slightly larger than posts 26, but are close enough in sizeto posts 26 that frame component 12 may be impacted to be properlyseated on distal end 18 of femur 16. While frame component 12 isdescribed and depicted herein as including posts 26, posts 26 are notnecessary to the function of frame component 12 and further embodimentsare envisioned in which posts 26 are absent.

Frame component 12 further includes shell contacting surface 27 havingcondylar bases 28, 30 connected by anterior bridge portion 32 andposterior bridge portion 34 (FIG. 3). In one exemplary embodiment,posterior bridge portion 34 replicates the cam of a Posterior Stabilizedfemoral implant. In another exemplary embodiment configured for aPosterior Cruciate Ligament Retaining femoral prosthesis, posteriorbridge portion 34 is absent. Additionally, ribs 36, 38 extend from shellcontacting surface 27 of frame component 12 to add rigidity andfacilitate retention and alignment of shell component 14 upon framecomponent 12, as discussed in detail below.

Referring to shell component 14, shell component 14 includes posterioroverhang 42, anterior overhang 43 (FIG. 2), and frame contacting surface40 forming condylar recesses 44. Condylar recesses 44 are separated fromoverhangs 42, 43 by tapered leads 46, 47, respectively, which facilitateattachment of shell component 14 to frame component 12. In one exemplaryembodiment, shell component 14 is formed from a plastic. For example,shell component 14 may be formed from an injection molded polymer. Byforming shell component 14 from a plastic or other polymer, the weightof shell component 14 and, correspondingly, femoral provisional 10 issignificantly reduced. Thus, a full complement of provisional componentsmade in accordance with the present invention is significantly lighterthan a full complement of standard provisional components, lessening theburden on operating room personnel and hospital staff who must transportthe same.

Shell component 14 also includes articulating surface 48 having condylarportions 50, 52 connected by anterior portion 54. Referring to FIG. 2,shell component 14 further includes grooves 56, 58 extending throughframe contacting surface 40 and overhang 43. Grooves 56, 58 areconfigured to receive and retain ribs 36, 38 of frame component 12,respectively, therein. Additionally, both grooves 56, 58 include anindentation (not shown) configured to matingly engage ribs 36, 38,respectively. Thus, receipt of ribs 36, 38 within the indentations ofgrooves 56, 58 provide for retention of anterior portion 54 of shellcomponent 14 upon anterior bridge portion 32 of frame component 12. Inone exemplary embodiment, the engagement of ribs 36, 38 with grooves 56,58 forms a snap-fit connection. Moreover, ribs 36, 38 and grooves 56, 58facilitate the alignment and seating of shell component 14 with framecomponent 12 prior to attachment.

Referring to FIGS. 1-3, condylar recesses 44 (FIGS. 1 and 2) of shellcomponent 14 are configured to receive portions of condyle bases 28, 30of frame component 12 therein. Specifically, condylar recesses 44 andtapered lead 46 are configured to engage posterior portions 60, 62 andtapered edge 64 (FIG. 2), respectively. Thus, posterior portions 60, 62and condylar bases 28, 30 of frame component 12 are in posterior matingengagement with condylar recesses 44 and tapered lead 46 of shellcomponent 14. In one exemplary embodiment, the interaction of condylarrecesses 44, tapered lead 46, posterior portions 60, 62 and tapered edge64 forms a snap-fit connection. To remove shell component 14 from framecomponent 12, a surgeon simply lifts up on anterior portion 54 of shellcomponent 14, for example, to release the snap-fit connection. Shellcomponent 14 may then be replaced by another shell component 14 havingdifferent characteristics.

To assemble femoral provisional 10 upon femur 16, femur 16 is initiallyresected, as described above, to form resected distal end 18. Apertures20 are then formed in resected distal end 18 of femur 16 and sized toreceive post 26 of frame component 12 therein. In one exemplaryembodiment, frame component 12 is selected from a plurality of framecomponents having different characteristics. With post 26 aligned withapertures 20, frame component 12 is impacted onto resected distal end 18of femur 16 until bone contacting surface 24 is in mating engagementwith resected distal end 18, as shown in FIG. 6. Referring to FIGS. 6and 7, once frame component 12 is securely seated on femur 16, one of aplurality of shell components 14 having characteristics which a surgeonbelieves would best accommodate a patient's natural anatomy is alignedwith and secured to frame component 12, as described in detail above.Alternatively, one of a plurality of shell components 14 may be securedto frame component 12 prior to seating frame component 12 on femur 16.Thus, once frame and shell components, 12, 14 are secured together, theassembly is impacted on femur 16 as described above. With shellcomponent 14 secured to frame component 12 and, correspondingly, femur16, a surgeon may perform trialing of femoral provisional 10.

In the event the surgeon determines that femoral provisional 10satisfactorily replicates the patient's natural anatomical movement,shell component 14 may be removed from frame component 12 and framecomponent 12 removed from femur 16. A nonprovisional femoral componenthaving characteristics which correspond to femoral provisional 10 isthen implanted using standard surgical techniques.

In the event a surgeon determines femoral provisional 10 does notsatisfactorily replicate a patient's natural anatomical movement, shellcomponent 14 may be removed from frame component 12, which provides thesole securement of shell component 14 to femur 16 as described in detailabove, and a different shell component 14 having differentcharacteristics may be attached to the same frame component 12. By usinga single frame component 12 capable of attachment to multiple shellcomponents 14, the need to impact and remove various frame components 12is eliminated. Thus, wear of resected distal end 18 of femur 16 islessened. Additionally, by providing for attachment of multiple shellcomponents 14 to a single frame component 12, the total number ofcomponents is lessened. The surgeon may then trial the new femoralprovisional 10. Once a surgeon has identified the one of a plurality ofshell components 14 that would satisfactorily replicate the patient'snatural anatomical movement, femoral provisional 10 may be removed fromfemur 16, as described in detail above, and the correspondingnonprovisional femoral component implanted.

Referring to FIG. 4, another exemplary embodiment of frame component 12and shell component 14 are depicted as frame component 70 and shellcomponent 72. Frame component 70 and shell component 72 include severalcomponents which are identical or substantially identical to componentsof frame component 12 and shell component 14, respectively, andcorresponding reference numerals are used to identify identical orsubstantially identical components therebetween. As shown in FIG. 4,frame component 70 includes openings 74 formed in condylar bases 28, 30and anterior bridge portion 32. Similarly, shell component 72 includesprojections 76 formed on condylar portions 50, 52 and anterior portion54. Projections 76 are sized and configured to be received with openings74 of frame component 70. Thus, as shown in FIG. 5, receipt ofprojections 76 of shell component 72 within openings 74 of framecomponent 70 provides a snap-fit connection between frame component 70and shell component 72.

To separate frame component 70 and shell component 72, a surgeon mayexert a force on anterior portion 54 of shell component 72, in adirection away from frame component 70, to disengage one of projections76 from one of openings 74. Once shell component 72 is removed fromframe component 70, a different shell component 72 having differentcharacteristics may be attached to frame component 70 in a similarmanner. In another exemplary embodiment, frame component 70 may includea projecting rib and shell component 72 a corresponding groove tofacilitate alignment of frame component 70 and shell component 72 tofacilitate proper seating and retention of shell component 72 on framecomponent 70.

While this invention has been described as having a preferred design,the present invention can be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and which fallwithin the limits of the appended claims.

What is claimed is:
 1. A modular provisional system comprising: a frame component configured to be secured to a distal end of a resected femur to provide a support surface, including a first substantially planar condylar base and a second substantially planar condylar base connected by an anterior bridge portion connecting anterior proximal portions of the first and second condylar bases and configured to abut an anterior femoral resection of the resected femur, and a posterior bridge portion connecting posterior proximal portions of the first and second condylar bases; wherein the anterior bridge portion including a plurality of engagement structures, the frame component including bone contacting surfaces configured to contact the distal end of the resected femur on three separate planes formed by resected surfaces including a distal resection, the anterior femoral resection and posterior femoral resection; and a plurality of shell components, each of said plurality of shell components configured to be releaseably secured to said support surface of said frame component by the plurality of engagement structures, said frame component and each of said plurality of shell components cooperable to form different provisional implants each of which replicate the characteristics of at least one nonprovisional component of a prosthesis system, different ones of said plurality of shell components releasably securable to the resected femur via the support surface of the frame component when the frame component is secured to the distal end of the resected femur.
 2. The modular provisional system of claim 1, wherein the plurality of engagement structures include an offset rib and each of said plurality of shell components further includes a groove formed therein, said groove of each of said plurality of shell components configured to receive said offset rib to releaseably secure each of said plurality of shell components to said frame component, wherein said offset rib is displaced medially or laterally from a centerline of said anterior bridge portion.
 3. The modular provisional system of claim 1, further comprising a plurality of frame components, each of said plurality of frame components configured to be secured to the distal end of the resected femur.
 4. The modular provisional system of claim 1, wherein said frame component is metallic and at least one of said plurality of shell components is plastic.
 5. The modular provisional system of claim 1, wherein at least one of said plurality of shell components is an injection molded polymer.
 6. The modular provisional system of claim 1, wherein at least one of said plurality of shell components further comprises a tapered lead adjacent a frame contacting surface of said at least one shell component of said plurality of shell components to facilitate seating said frame component against said frame contacting surface. 